Bore holes with very small tolerances, i.e., tolerances smaller than tolerance class IT6, is difficult to achieve with conventional reamers, such as solid carbide reamers or brazed carbide reamers. Therefore, one needs an adjustable reamer.
There are two kinds of adjustable reamers: 1) the single blade reamer with an adjustable insert, and 2) an expandable multi-flute reamer. Referring now to FIG. 6, a conventional expandable multi-flute reamer 100 has a shank 102, and a cutter head 104 with cutters 106. A conical screw 108 is screwed into the shank 102 such that a conical head 110 of the screw 108 contacts a conical wall 112 and causes expansion of the cutters 106. Coolant and lubricant is supplied by an axial channel 114 that axially extends through the shank 102. In an attempt to provide adequate coolant and lubricant to the cutters 106, a ring channel 116 is provided between the conical screw 108 and a wall 118 of the cutter head 104. Outlet channels 120 extend through the wall 118 of the cutter head 104 at an angle between thirty (30) and forty-five (45) degrees towards the front end of the cutter head 104.
It has been found that the shank 122 of the conical screw 108 interferes with the supply of the coolant and lubricant such that an optimum, strong supply of coolant and lubricant is not provided to the cutting head 104. In addition, the shank 122 of the conical screw 108 does not leave enough design space for proper placement of the coolant channels 116 to accurately supply the coolant and lubricant to the cutter head 104. Therefore, it is desirable to provide an adjustable reamer that overcomes the shortcomings of the prior art.